Currently many dual pawl ratchet mechanisms are known and used. Typically, these mechanisms are incorporated into handtools, such as wrenches and/or screwdrivers, or the like, so that there is a drive portion engageable with, for example, a bolt head. A first drive direction may be selected for the dual pawl ratchet mechanism so that use of the handtool provides torque when engaged with the bolt head and rotated in a first direction while slipping or ratcheting when rotated in a second direction. A second drive direction may be selected for the dual pawl ratchet mechanism that is opposite the first drive direction, and that provides torque and slip in the opposite directions.
In operating the reversible dual pawl mechanism, there is typically a manually actuable portion, commonly referred to as a reversing lever, that effects the engagement of one pawl and the disengagement of a second pawl, the actuable portion being commonly referred to as a reversing lever. The drive direction for the drive portion is dependent on which of the two pawls is engaged.
The reversing lever is typically rotated about an axis that is generally perpendicular to a face or side of the ratchet head to engage and dis-engage the pawls and, thus, to select the drive direction. The axis of rotation for the reversing lever is generally parallel to the axis of rotation of drive portion that provides the torque.
One of the problems with these handtools is the amount of rotation of the reversing lever. It is not uncommon to provide a spring and ball assembly, the spring biasing the ball into a detent, for defining the positions for the reversing lever. If the ball and detent cooperation is significant (such as due to a deep detent and spring with a high spring constant), the detent and ball can become worn or damaged. On the other hand, if the cooperation is slight, the mechanism may not provide a clear tactile indication of reaching a selected position and/or may permit accidental shifting from the selected position, again leading to damage.
When the ball is partially positioned over or within the detent, the spring can act to promote the ball being properly received in the detent. That is, the pressure of the ball against an edge of the detent serves to direct the reversing lever towards or to one of the proper, predetermined positions. However, due to the small size of the components, the ball must be nearly in the proper position for this to have any effect. More broadly, if the ball is not positioned nearly in the proper position, the spring pressure has no effect.
One of the important aspects of these types of tools is manufacturing complexity and costs. In using these ball/detent features, the manufacturing complexity and costs are increased. As an example of this, the spring is first inserted into a blind hole formed either in the tool head or in the reversing mechanism, and then the ball is positioned on the end of the spring prior to assembly with the other components. In high speed manufacturing operations, ensuring the ball remains in the proper place as the spring is compressed to allow the other components to be assembled is no small endeavor.
In another aspect of manufacturing costs and complexity, internal components are often utilized that allow one or more other components to be properly located. If these internal components are to be fixed in a specific position, it is common to have to provide a mechanical attachment such as screws.
Accordingly, there has been a need for an improved dual pawl mechanism and reversing method.